JE 16井是安第斯石油公司位于厄瓜多尔东北部的一口重点参数井.地层中存在大段泥岩层且造浆严重,页岩层易吸水垮塌,另外还有两段厚度不等的砾石层,地质情况较为复杂.井斜大、造斜点高、水平位移大,存在井眼清洁、井壁润滑难题.防塌钻井液体系是针对该区块二开Orteguaza和Tiyuyacu层页岩坍塌和咖啡色泥岩吸水膨胀而开发的防塌钻井液体系.在全部采用符合当地环保要求的材料同时,有效解决了泥岩段坍塌和砾石层段起下钻遇阻的难题,保证了钻井质量,起下钻无遇阻,二开套管一次下到井底,二开钻井周期比钻井设计提前2.5 d.

厄瓜多尔Sacha油田TIYUYACU层存在上下2个砾石层,上砾石层厚度约为61 m,下砾石层厚度超过200 m.该地层研磨性强、渗透性强,对压力敏感,是钻井过程中出现复杂甚至事故的高发地层.本文通过分析Sacha 44MD井在砾石层出现的问题,从钻井液的角度找出问题出现的原因,提出优化方案.通过降低体系密度,加强封堵性等措施,实现了砾石层的安全快速钻进,自Sacha 44XD井以后,在砾石层钻进顺利,起下钻、下套管等也未出现遇阻等复杂情况,为解决砾石层钻进难题积累了宝贵的经验.

随着石油行业环保意识的增强和环保标准的提高,岩屑处理成为各大油田面临的一大难题,岩屑回注技术是较为可靠的解决方案之一,可实现钻井现场零排放.根据地震和测井数据分析,NAPO-T层砂岩发育良好且无油气显示,上下层均为页岩层,满足地质隔离要求,适合选做岩屑回注层.TMBD-00XD井是厄瓜多尔Tambococha油田完钻的第一口井,为“S”型三开井身结构,井深1 816.6 m,最大井斜14.5°,承担着该区块全部钻屑和废弃钻井液的回注任务.该井自启动岩屑回注工作以来,已累计回注岩屑和废液近1.1×105 m3,满足两部钻机同时作业产生的岩屑的回注要求,彻底处理了岩屑和废液,避免了二次损害,且处理成本低,在高环境敏感地区有着良好的推广应用前景.

针对长庆气田碳质泥岩段井壁失稳造成井下复杂频发、侧钻率高的问题,开展了岩样的微观结构、阳离子交换容量、矿物组成及理化性能分析,测试了钻井液对岩石力学特性及坍塌压力的影响,确定了碳质泥岩坍塌机理及防塌钻井液技术研发思路.通过实验优选出封堵剂、抑制剂等钻井液处理剂,综合采用纳米乳液、软硬结合的封堵技术,形成了强封堵强抑制高性能钻井液体系配方.该体系的HTHP滤失量≤6mL,API滤失量≤2mL,石盒子砂岩封堵率≥85％,人造岩心线性膨胀降低率≥60％.在长庆气田现场试验18口井,钻遇碳质泥岩后侧钻率降低至16.7％,平均钻井周期缩短30d,达到预期效果,该钻井液技术满足长庆气田碳质泥岩井段安全钻进的需要.

靖平69－12井目的层马五1－3，埋藏深度3700 m，属长南气田第一口三开结构水平井，刘家沟组漏层和“双石”层与山西组、太原组以及本溪组等煤层处于同一裸眼井段，裸眼段长，防漏与防塌的安全密度窗口窄，是典型的塌漏同段井。针对该区块地层特点，研制出了抑制性强、封堵性好等特点的强抑制成膜封堵钻井液体系。现场应用结果表明，该体系表现出良好的抑制防塌性、润滑防卡性和成膜封堵特性，滤饼薄而韧。在整个斜井段施工过程中井壁稳定，起下钻不阻不卡，克服了上部裸眼段长时间浸泡所带来的井壁不稳定风险，防止了地层漏失，解决了长裸眼段下存在的井壁坍塌、润滑防卡等技术难题，保证了3460 m多的长裸眼井段的井眼稳定和177．8 mm技术套管一次性下到预定位置。

桃平1井是中石油2011年部署的30口重点风险气探水平井之一,为长庆油田第一口下古马五5无导眼风险气探水平井.该井为苏里格下古水平井最简化的井身结构,斜井段裸眼长达3950m;自造斜点开始全井段使用哈里伯顿FEWD,大斜度井段需要穿越多套煤层,存在许多钻井液难题.通过在斜井段使用复合盐聚磺钻井液体系,有效地控制了“双石层”的垮塌,避免了PDC钻头泥包;首次试验了防塌封堵剂G314-FDJ,突破了原有苏里格下古水平井大斜度井段安全穿越煤层必须保证密度在1.30g/cm3以上的共识,以1.23 g/cm3低密度安全穿越太原、本溪组多个大段煤层,避免了因密度高引起刘家沟二次漏失;水平段使用无土相暂堵钻井液体系,具有良好的润滑性,保证了水平段的快速钻进和筛管安全顺利下入,创造了长庆苏南区块多项最优指标.

The well of Taoping1 is one of the 30 key exploration horizontal wells of CNPC, it is also the first exploration horizontal well without pilot hole to drill Xiagu Ma5-5 formation in Changqing oilfield. The operation of drilling fluid has many challenges because of the most simplified structure, the inclined open hole of 3, 950 m long that is combined of many sets of coal layer, and using Halliburton FEWD from the kick-off point. The compound salt polysulfonate drilling fluid system is applied in this well to avoid collapsing and PDC bit balling in Shiqianfeng and Shihezi formations. For the first time, the plugging material G314-FDJ is used to drill through Taiyuan and Benxi coal layers safely with drilling fluid density of 1.23 g/cm3 (normal density is over 1.30 g/cm3) that can prevent lost circulation in Liujiagou formation. In horizontal section, the clay-free temporary plugging drilling fluid system is used to ensure drilling fast and casing safety.

The application of nitrogen drilling at the highly abrasive gas-bearing Xujiahe Formation of the LG area is critical for the ROP improvement,reservoir protection,prevention of downhole explosion,and for further exploration and development in this area.Hereby,according to the practices and experiences from the nitrogen drilling in this formation on many wells,we summarized the equipments used,the technical challenges encountered,and the measures adopted as follows:1) the drilling rate should be controlled to be over 5 min/m in order to avoid sticking;2) if serious sticking occurs,work the drill string at a controlled pull force,and keep circulating continuously till no obstruction in the annulus,then readjust the work distance of the drill string in order to free it.The successful application of nitrogen drilling at the Xujiahe formation has proved that nitrogen drilling can not only improve the ROP effectively,but avoid downhole fires or explosions when drilling through gas zones with air.

Gas drilling has been widely used in northeast Sichuan area gradually.It not only can greatly increase the penetration rate,shorten the construction cycle,reduce drilling costs,but also can improve the rate of exploratory wells and enhance recovery ratio.Anticipating the complex characteristics of gas drilling in the course of drilling,using the immediate symptoms during before or during the accident occurred to forecast and treat down hole accidents timely is key of gas drilling.The paper summarized some symptoms of yielding water,borehole collapse and hole deviation in northeast Sichuan area by practice.Meanwhile,the method on how to diagnose complicated downhole problems according to these symptoms was described,and some processing methods on formation water output,hole sloughing,borehole inclination and so on were put forward.

Air drilling has two advantages of increasing ROP and formation protection, and the air drilling is developed rapidly in China. With the air drilling, a lot of new oil and gas resources have been discovered. Although the air drilling has its advantages, the limitations of the air drilling process must also be regarded. The technology of air drilling had improved rapidly with the air drilling was taken into account by the petroleum industry, but excessive formation water, wellbore stability, sulfide formation, downhole fire etc. issues have restricted the air drilling. Integrating the field trial in SuLiGe area of ChangQing, the paper analyses the complex condition accompanying air drilling and have formed a series methods dealing with the complicate problem in air drilling.